1. Field of the Invention
This invention relates to a method of selectively reducing excessive production of aqueous fluids within subterranean formations.
2. Summary of the Prior Art
The production of water and aqueous fluids in oil and gas wells can present a variety of problems. As gas and oil are removed from a producing well, water begins to push through the formation into the well where it is eventually produced along with the oil and gas. This reduces the amount of oil and gas that can be recovered. Once the water is removed from the well, it must be separated from the produced hydrocarbons and disposed of in an environmentally safe manner. This adds additional expense to the recovery operation. It is therefore advantageous to treat the well to minimize water production.
Prior art methods that have been used to restrict water production include the gelation of polyvinyl alcohol (PVA), polyacrylic acid and the condensation polymerization of phenol and formaldehyde within the formation's pore channels. These processes are designed to damage the pore channel within the formation matrix and restrict fluid movement through the channels. Another technique involves loading a subterranean area adjacent to the wellbore with a barrier, such as concrete, resin or particulate matter, so that the loaded area is effectively plugged. The area above the loaded area is then perforated to begin production. Unfortunately, these prior art methods are nondiscriminating and tend to damage both the hydrocarbon and water producing channels.
Another problem with many of the water control compounds used in reducing water production in oil and gas wells are that they are unstable in acids and heavy brines which are frequently found within oil and gas wells. Furthermore, many degrade with increased temperature. Thus these compounds are rendered useless in many downhole applications.
What is needed is a method for reducing the production of water in oil and gas wells by selectively treating the water bearing formations without damaging the hydrocarbon bearing formations, and which is not affected by the acidic or alkaline conditions, salt content or high temperatures which are frequently found within these wells.